#ID:2115070128
#Name:徐廉杰
###problem1

def y(a,b):
    s=a*b
    s1=s**(1/3.0)
    return (10+8*s1)/(2*a+3*b)

###end

###problem2

a,n =map(int, input().split( ))
s=0
for i in range(1,n+1):
    s=s+a*10+i
print(s)

###end


###problem3

import re
str_1=''
list_1=[]
list_2=[]
dict_1={}
with open("a.txt",'r') as f:
    for i in f:
        str_1+=i
        list_1=re.findall(r'[A-Z|a-z]+',str_1)
for i in list_1:
    if i in dict_1:
        dict_1[i]+=1
    else:
        dict_1[i]=1
list_2=sorted(dict_1,key=lambda x:dict_1[x],reverse=True)
    
with open("b.txt", 'w') as f2:
    for i in list_2[:11]:
        f2.write(i+' ')

###end


###problem4

def convert(path,string):
    res={}
    list_1=[]
    with open(path,'r') as f:
        for i in f:
            list_1.append(i.strip().split(' '))
        for i in list_1:
            res[i[1]]=i[0]
    for i in string:
        if i in res:
            print(i,'->',res[i])

###end


###problem5
def my_yield(string):
    j=1
    a=str1[0]
    c=len(str1)
    b=str1[c-1]
    for i in range(ord(a),ord(b)+1):
        yield chr(i),chr(ord(b)+1-j)
        j+=1
str1=''    
str1=input()

for i in my_yield(str1):
    print(i,end='')
     

###end

###problem6


###end